Rotary converter for electric welding.



A. M. HOFFMAN. noun coNvEn'rEn ron nLoTmo WELDING.

APPLIOATIGI YILBD DBO. 23, 1901'. 904,782. Patented Nov. 24, lads. 2 SHEETS-SHEET 1.

A. M. HOFFMAN.

ROTARY CONVERTER FOB. ELECTRIC WELDING.

APPLIOATIOI FILED DBO. 23, 1907.

904,782. Patented Nov. 24, 190s.

B SHEETS-SHEET 2.

nun

A M raffina n.

ARTHUR. M. HOFFMAN, 0F JOHNSTOWN, PENNSYLVANIA.

ROTARY coma'rnn ron nmo'rnrc WELDING.

specification o: Letters Patent.

Patented Nov. 24, 190B appresso mea nmmbn sa, 1am. sarna n. mada To all whom 'it ma/y concern:

13e it known that I, AnTHUn M. HOFFMAN, citlzen of the United States, residing at Johnstown, in the county of Cambria and State of Pennsylvania, have invented certain new and useful Improvements in Rotary Converters for Electric Welding, of which the following is a specification..

The present invention relates to a novel device for converting direct currents into alternating currents, and while it may be employed in such a capacity wherever it is desired to brin about such a result, it is particularly deslgned for use in connection with electric rail Welding outfits.

The object of the invention is to provide a converter of this character which is simple and compact in its construction and can be readily employed for iield Work.

The invention further contemplates a novel construction whereby a continually varying resistance is introduced into the circuit of the alternating current, such a result being desirable under certain conditions of service.

For a full description of the invention and the merits thereof and also to acquire a knowledge of the details of construction and the means for effecting the result, reference is to be had to the following description and accompanying drawings, in which:

Fi ure 1 1s a vertical longitudinal sectiona view through the device, the rotor being shown in side elevation. Fie. 2 is an endvview of the device, portions thereof being broken away. `Fig. 3 is abottom plan view of the device. Fig. 4 is a detail view of the rotor. Fig. 5 is a diagrammatic view showing a modification.

Corresponding and like parts are referred to in the followin description and indicated in all the views o the drawings by the same reference characters. y

Specifically describing the present embodiment of the invention the numeral 1 designates a casing which may be formed of cast iron or other suitable material and is normally closed by means of acover 2, the said casing being designed to contain oil or like liquid for the purpose of preventing the formation of arcs as will be more apparent as the description proceeds. Journaled within the casing 1 is a shaft 3 one end of which (projects upon the exterior of the casing an is designed to receive rotary move- 'ment from any suitable source of power.

Arraned within the casing and mounted upon t e shaft 3 is a rotor 4 which is of approximately cylindrical shape andis formed of some insu ating material such as hard wood. The internal diameter of the opening 5 through this rotor is greater than the diameter of the shaft 3 and the said rotor is designed to be entirely sup orted by contacts as will be clearly set orth hereafter. In the present instance the opposite ends of the rotor are beveled and have the plates 6 applied thereto, one of the said plates carrying a projection 7 designed to be engaged b an arm 8 projecting laterally from the sha and rigid therewit so as to cause the rotor to revolve with the shaft. Applied to opposite ends of the rotor 4 are the collectoi rings 9l and 9" which are designed to be in electrical connection with the terminals of the circuit for the direct current. In the present instance these collector rings engage the brushes or contact blocks 10 and 10b upon opposite sides o f the bottom of the casing 1,A the said brushes serving to support the entire weight of the rotor and the brush 1()a being connected to the trolley wire while the brush 10" is grounded. For the urpose of holding the collector rings in a c ose enagement with the brushes 10 and 10 bearlng blocks 11 of insulating material are p1o vided which are spring pressed against the upper portion of the rotor. As shown on the drawings two of these bearing blocks 11 are located at each end of the rotor, correspondin bearing blocks being connected by thelongltudinal sprin stri s 12 having intermediate portions t creo secured to the cover 2. It will thus be apparent that when the cover is in position the said blocks will engage the collector rings and tend to force the rotor 4 downwardly so as to produce a close contact between the said collector rings and the brushes.

A series of plates are arranged upon the surface of the rotor between the collector rings, alternate plates having an electrical connection with the respective collector rings. In the present construction four of these plates are provided, the plates 13 b'eing connected 4to the collector ring 9* while the plates 13IJ are connected to the collector' ring 9*. Arran ed upon each sido of the lower portion o the casing 1 is a plurality' of contacts designed to engage the plates 1:5 and 13b the contacts 14, 14, 14"', 14, 14e and 14 being connected with one ot' the terminals of the circuit for the alternating current while the contacts 15, 15", 15, 15d, 15 and 15 are connected to the opposite terminal of the said circuit. `These two sets of contacts are spaced apart a distance corresponding to that between adjacent plates 13 and 13" so that when one set of contacts establishes electrical connection with one of the plates 13, the opposite set of contacts will in a similar manner establish connection with one of the plates 13". As the rotor is revolved it will be readily ap arent that this condition will be constanty reversed and an alternating current produced within the circuit 16, the frequency of the current depending upon the speed with which the rotor is caused to revolve.

It will be observed that the various contacts of each series are insulated from the casing 1 by means of suitable strips of insulatlng material 17 and are held in position by bolts 18 which extend through the casing but are insulated therefrom. It will also be observed that the individual contacts of each series are connected by lneans of resistances R, the end contact 14 of one series being directly connected to one of the terminals of the circuit 16 for the alternating current while the end contact 15' ofthe opposite series is in a similar manner directly connected to the opposite terminal of the circuit. In the operation of the machine the various contacts of each series are designed to be brought successively into electrlcal connection with the plates 13 and 13b so as to radually bring the various re sistances R 1nto`the circuit and gradually cut them out of the same during each c cle. For this purpose the adjacent longitu inal edges of the plates 13 and 13b are given a stepped formation so that they gradually diverge from each other from one end of the rotor toward the op osite end. One of these steps is provided or each of the contacts and in the present instance the longitudinal edges of each plate are formed with steps 19g 19h, 19, 19d, 19e and 19f. With this Construction it will be readily apparent that as the rotor 4 is revolved, the contact members 14' and 15 will first engage the steps 19" of adjacent plates 13 and 13b, and that the entire current within the circuit 16 will be forced to pass through all of the resistances R. As the rotor continues to revolve the contact members 14h and 15" will be brought into engagement with the steps 19b and one of the resistances R of each series will be cut out of the circuit 16. In this manner it will be readily apparent that all of the various resistances will be successively cut out as the rotor revolves and that when the contact members 14" and 15 are brought into engagement with the steps 1%)r there will be no resistance in the circuit 1G since the current will pass directly into the same. ln an exactly analogous manner the resistances R will be again successively introduced in the circuit 16 as the various contact members move away from the corresponding steps of the lplates 13il and 13".

When it is desired to use the alternating current for rail Welding purposes as in the present instance, the primary coil of a transformer 2() is introduced into the circuit 16 and the voltage thereby stepped down the desired amount and the ampera e correspondingly increased. It is again esired to call attention to the fact that the casing 1 is filled with oil within which the rotor 4 operates, the said oil tending to prevent the formation of arcs and enabling the device to be employed in connection with high tension currents.

A modification is shown in Fig. 5 in which the plates of the rotor are not given a stepped formation but are in the nature of bars as indicated at 13. The contactimembers however are gradually decreased in length from one end of the machine to the opposite end, the various resistances R being interposed between the adjacent contact members in a manner identical with that heretofore described. These contact members are designated by the reference characters 21, 21, 21,""21d, 21E and 21', the member 21a being the longest of the series and the member 31I bein the shortest. As the rotor is revolved it will be readily apparent that when the contact member 21 engages the plates upon the rotor all of the various resistances R will be in series with the transformer, and that when the contact members 2lb are brought into electrical connection with the plates, one of the resistances in each of the series of contact members will be cut out of the circuit.; In this manner it will be readily apparentY that all of the resistances will be successively cut out of the alternating current circuit and again cut into the circuit for every phase of the alternating current. The construction of the remainder of the machine is identical in the modification with that of the first described embodiment of the invention` and the only difference resides in the fact that the contact members or brushes of the alternatin current circuit are arranged in a ste pe series instead of stepping the longitu inal edges of the plates u on the rotor.

Having thus descri ed the invention, what is claimed as new is:

1. A device for converting a direct current into an alternating current comprising a rotor, a series of plates carried by the rotor,

cut the resistances in and out of the' circuit' during each cycle.

2. device for converting a direct current into an alternating current comprising a rotor, a plurality of lates carried by the rotor, alternate plates iavino electrical connection with the terminals o? the direct current circuit and the edges of the plates having a stepped formation, a series of contacts in electrical connection with each terminal of the alternating current circuit, and resistances interposed between the individual contacts of each series, the stepped formation of thel lates bringing the various contacts of eaci series into successive engagement therewith so as to cut the resistances in and out of the circuit during each cycle.

3. A device for converting a direct current into an alternating current comprising a rotor, collector rings mounted upon the rotor and having electrical connection with the opposite terminals of the direct current circuit, a series of plates carried by the rotor, alternate plates being in electrical connection with the respective collector rings, a series of contacts at each terminal of the alternating current circuit, and resistances interposed between the individual contacts of each series, the various contacts of each series being designed to be brought successively into and out of engagement with the plates so as to cut the resistances in and out of the alternating current circuit.

4. A device for convertingr a direct current into an alternating current comprising a rotor. collector rings mounted upon the rotor and having electrical connection with the opposite terminals of the direct current circuit. a plurality of plates carried by the rotor and having the edges thereof stepped, alten nate plates being in electrical connection with the respective collector rings, a series of contacts at each terminal of the alternating current circuit, and resistances interposed between the individual contacts of each series, the stepped formation of the plates causing the individual contacts to be brought successively into and out of engagement With the plates so as to cut the resistances in and out of the alternating current circuit.

5. A device for converting a direct current into an alternating current comprising a plurality of plates having the edges thereof stepped, alternate plates having electrical connection with the opposite terminals of the direct current circuit, a series of contacts at cach terminal of the alternating current circuit, resistances interposed between the various contacts of each series, and means for moving the before mentioned plates with respect to the contacts, the stepped formation of the plates causing the individual contacts of each series to be successively brought'in and out of engagement therewith so as to cut the resistances in and out of the alternating current circuit.

6. A device of the character described comprising a shaft, a rotor loosely mounted upon the shaft, contact members serving to support the rotor, and means for causing the rotor to revolve with the shaft;

7. In a device of the character described, the combination of a shaft, a rotor loosely mounted upon the shaft, the opening through the rotor bein larger than the shaft, means for causing tie rotor to revolve with the shaft, and contact members serving to support the rotor.

8. In a device of the character described, the combination of a shaft, a rotor provided with an opening receiving the shaft, said opening being larger than the shaft, means for revolving the iotor, contact members serving to support the rotor, and yielding means for holding the rotor in engagement with the contacts.

9. In a device of the character described, the combination of a shaft, a rotor provided with an opening receiving the. shaft and larger than the same, means for revolving the rotor, collector rings mounted upon the rotor, contact members engaging the collector rings to support the rotor, a plurality of plates carried by the rotor, alternate plates having electrical connection with the respective collector rings, and contacts for coperating with the plates to convert a direct current into an alternating current.

10. In a device of the character described, the combination of a shaft, a rotor provided upon an opening receiving the shaft and larger than the same, means for revolving the rotor, collector rings mounted upon the rotor, contacts engaging the collector rings to support the rotor and having electrical connection with the terminals of a direct current circuit, blocks yieldingly engaging the collector rings to hold the same in close engagement with the before-mentioned contacts, a plurality of plates carried by the rotor, alternate plates being in electrical connection with the respective collector rings, and contacts having electrical connection with the terminals of an alternating current circuit and cooperating with the before-mentioned plates.

11. A device for converting a direct current into an alternating current comprising a plurality of plates, alternate plates having electrical connection with the oppositeterminuls of the direct current circuit, :L series nl' mntm'ts nt mn'h tvrmnnl of tlm alturnuting' 'nrrunt virunt, rvsistzrncus intcrpuscr] ln-ttwwn thu vnl-inns funtuuts nl' mu'll Hrvs, :md nnmns for nmvilml the lml'urc-mvnttimn-I platos with respect tu the contacts, tlnl 1untnctsn'l' vzmh series being successivi-ly brought into and out'y of engagement with the plutos :ulti-Hurting rmrrsnt circuit.

1n testimony whmuf l unix my signature in [nescnru nl' two witnvssvs.

AR'IIIUR M. HOFFMAN. Witnesses:

JmlN InMm-m, Imslrr M l x r: Nmcn.

t l.. f4.1 

